AB0597 FDG-PET/CT IN THE DIAGNOSE AND FOLLOW UP OF TAKAYASU VASCULITIS
Authors: B. Gudbrandsson, Ø. Palm, Ø. Molberg, H. Giltvedt, M. Revheim
Journal: Annals of the Rheumatic Diseases (2022)

Background Takayasu vasculitis (TAK) is a chronic disease, where clinic and serological markers as CRP/ESR may fail to predict development of new vascular lesions in the disease course (1). Similarly, 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) studies show conflicting results on the association between vessel uptake of FDG and clinical and laboratory finding. A study on new FDG-PET activity scoring system, PETVAS was newly published but has not been validated in other cohorts (2). To date there are limited data on FDG-PET/CT finding at time of diagnoses before treatment induction and 18-FDG uptake and development of new stenosis during follow up. Objectives The goal of this study was to see; 1) FDG-PET/CT uptake in newly diagnosed patients before any treatment start 2) FDG-PET/CT uptake and development of new vascular lesions during follow up magnetic resonance angiography (MRA) 3) assess PETVAS score before and after treatment induction. Methods All patients in a population-based TAK cohort with FDG-PET/CT at the time of diagnoses before treatment induction were identified. Disease activity was assessed with the NIH activity score (1). Patients had to have clinical, laboratory and MR-angiography prior to/or right after FDG-PET/CT and a minimum of one follow up MRA. The clinical report from the FDG-PET/CT and MRA were reviewed and arteries/aorta regions with reported pathological uptake and stenosis/aneurysm were registrated. Images were reviewed and uptakes in 16 arteries/aorta regions of interest (supraaortic arteries, aorta, iliaca and femoral arteries) scored from 0-3, where 0 represent no uptake, 1 less then liver, 2 same as liver and 3 higher than liver and finally summarized these to PETVAS score. Results Twenty-three patients fulfilled the study’s inclusion criteria. Twenty-one of the patients were females (91%) and twenty-two were European Caucasian. The mean age was 39.3 (SD 14) at the time of diagnose (Table 1). Five patients were in clinical and laboratory remission at diagnose (NIH=0). Correspondently, none of them had sign of active FDG vessel uptake at PET-CT. They had a median 7 in PETVAS (range 0-13). The remaining 17 patients had clinical active disease (NIH&gt;1) at diagnoses. All 17 patients had uptake on PET/CT in at least one artery/aorta region. The mean PETVAS score at diagnosis was 21.5 (SD 8). At last imaging the patients had developed median 2 new lesions. All the arteries that developed new lesion had active uptake on the original PET/CT. Fourteen patients had FDG PET/CT after treatment start. The PETVAS score decreased from 22.4 (SD 8.7) to 10.7 (SD 6.8) after treatment start (p&lt;0.001). Table 1. Patient Age at pet 1 NIH 0-4 Crp PETVAS1 PETVAS 2 Treatment at PET2 1 15 1 20 16 2 64 2 33 16 9 predn 10 mg, mtx 15 mg 3 26 3 207 18 0 predn 15 mg, INF 4 34 3 13 18 7 predn 2.5 mg, mtx 20 mg, INF 5 40 3 317 32 13 predn 10 mg, mtx 15 6 48 3 12 22 16 predn 5 mg, mtx 20 7 55 3 59 37 20 predn 10 mg, mtx 15 8 54 3 182 35 25 predn 5 mg, mtx 15 9 21 4 19 13 3 predn 5 mg, mtx 20 10 36 4 145 18 4 predn 7.5 mg, mtx 17.5 mg 11 27 4 33 14 7 predn 5 mg, mtx 22.5 12 39 4 7 15 7 predn 10 mg, mtx 22.5 mg 13 31 4 75 21 11 predn 10 mg, mtx 25, INF 14 39 4 80 24 16 predn 7.5 mg, mtx 20 mg 15 63 4 106 35 16 predn 10 mg, mtx 20 16 22 4 120 20 17 27 4 263 21 Conclusion All patients with clinical active disease at diagnoses had pathological FDG uptake. Only arteries with increased FDG uptake in the vascular wall subsequently developed new lesion. The study also showed that the PETVAS score fell significantly after treatment induction. References [1]Kerr GS, Hallahan CW, Giordano J, Leavitt RY, Fauci AS, Rottem M, et al. Takayasu arteritis. Annals of internal medicine. 1994;120(11):919-29. Epub 1994/06/01. [2]Grayson PC, Alehashemi S, Bagheri AA, Civelek AC, Cupps TR, Kaplan MJ, et al. (18) F-Fluorodeoxyglucose-Positron Emission Tomography As an Imaging Biomarker in a Prospective, Longitudinal Cohort of Patients With Large Vessel Vasculitis. Arthritis &amp; rheumatology (Hoboken, NJ). 2018;70(3):439-49. Epub 2017/11/18. Disclosure of Interests None declared